Methods for marking a biopsy site

ABSTRACT

Implantable devices and methods of use are disclosed for marking the location of a biopsy or surgery for the purpose of identification. The methods include providing a biodegradable radiodense implant and taking a tissue sample from a biopsy site within a breast of a patient. The biodegradable implant is then positioned at the biopsy site. The tissue sample is tested and the biopsy site is then relocated. In one embodiment, the entire implant is radiodense. In another embodiment, the entire implant is biodegradable. Methods of using a biodegradable implant having a radiodense material and a biodegradable implant that is visible using an imaging system are also included.

This is a continuation of U.S. application Ser. No. 09/954,646, filedSep. 18, 2001, which is a continuation of U.S. application Ser. No.09/776,125, filed Feb. 2, 2001 now U.S. Pat No. 7,044,957, which is acontinuation of U.S. application Ser. No. 08/858,389, filed May 19,1997, now issued as U.S. Pat. No. 6,228,055, which is a continuation ofU.S. application Ser. No. 08/308,097, filed Sep. 16, 1994, nowabandoned. All of the above patents and applications are expresslyincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

This invention relates to methods and devices for marking and definingparticular locations in human tissue, and more particularly relates tomethods and devices for permanently defining the location and margins oflesions detected in a human breast.

It is desirable and often necessary to perform procedures for detecting,sampling, and testing lesions and other abnormalities in the tissue ofhumans and other animals, particularly in the diagnosis and treatment ofpatients with cancerous tumors, pre-malignant conditions and otherdiseases or disorders. Typically, in the case of cancer, when aphysician establishes by means of known procedures (i.e., palpation,x-ray, MRI, or ultrasound imaging) that suspicious circumstances exist,a biopsy is performed to determine whether the cells are cancerous.Biopsy may be an open or percutaneous technique. Open biopsy removes theentire mass (excisional biopsy) or a part of the mass (incisionalbiopsy). Percutaneous biopsy on the other hand is usually done with aneedle-like instrument and may be either a fine needle aspiration (FNA)or a core biopsy. In FNA biopsy, very small needles are used to obtainindividual cells or clusters of cells for cytologic examination. Thecells may be prepared such as in a Papanicolaou (Pap) smear. In corebiopsy, as the term suggests, a core or fragment of tissue is obtainedfor histologic examination which may be done via a frozen section orparaffin section. The chief difference between FNA and core biopsy isthe size of the tissue sample taken. A real time or near real timeimaging system having stereoscopic capabilities, such as thestereotactic guidance system described in U.S. Pat. No. 5,240,011, isemployed to guide the extraction instrument to the lesion. Advantageousmethods and devices for performing core biopsies are described in theassignee's co-pending U.S. patent application Ser. No. 08/217,246, filedon Mar. 24, 1994, and herein incorporated by reference.

Depending upon the procedure being performed, it is sometimes desirableto completely remove suspicious lesions for evaluation, while in otherinstances it may be desirable to remove only a sample from the lesion.In the. former case, a major problem is the ability to define themargins of the lesions at all times during the extraction process.Visibility of the lesion by the imaging system may be hampered becauseof the distortion created by the extraction process itself as well asassociated bleeding in the surrounding tissues. Although the lesion isremoved and all fluids are continuously aspirated from the extractionsite, it is likely that the process will “cloud” the lesion, thusimpairing exact recognition of its margins. This makes it difficult toensure that the entire lesion will be removed.

Often, the lesion is merely a calcification derived from dead abnormaltissue, which may be cancerous or pre-cancerous, and it is desirable toremove only a sample of the lesion, rather than the entire lesion, toevaluate it. This is because such a lesion actually serves to mark ordefine the location of adjacent abnormal tissue, so the physician doesnot wish to remove the entire lesion and thereby lose a critical meansfor later re-locating the affected tissue. One of the benefits to thepatient from core biopsy is that the mass of the tissue taken is small.However, oftentimes, either inadvertently or because the lesion is toosmall, the entire lesion is removed for evaluation, even though it isdesired to remove only a portion. Then, if subsequent analysis indicatesthe tissue to be malignant (malignant tissue requires removal, days orweeks later, of tissue around the immediate site of the originalbiopsy), it is difficult for the physician to determine the preciselocation of the lesion, in order to perform necessary additionalprocedures on adjacent potentially cancerous tissue. Additionally, evenif the lesion is found to be benign, there will be no evidence of itslocation during future examinations, to mark the location of thepreviously removed calcification so that the affected tissue may becarefully monitored for future reoccurrences.

Thus, it would be of considerable benefit to be able to permanently markthe location or margins of such a lesion prior to or immediately afterremoving or sampling same. Marking prior to removal would help to ensurethat the entire lesion is excised, if desired. Alternatively, if thelesion were inadvertently removed in its entirety, marking the biopsysite immediately after the procedure would enable re-establishment ofits location for future identification.

A number of procedures and devices for marking and locating particulartissue locations are known in the prior art. For example, location wireguides, such as that described in U.S. Pat. No. 5,221,269 to Miller etal., are well known for locating lesions, particularly in the breast.The device described by Miller comprises a tubular introducer needle andan attached wire guide, which has at its distal end a helical coilconfiguration for locking into position about the targeted lesion. Theneedle is introduced into the breast and guided to the lesion site by animaging system of a known type, for example, x-ray, ultrasound, ormagnetic resonance imaging (MRI), at which time the helical coil at thedistal end is deployed about the lesion. Then, the needle may be removedfrom the wire guide, which remains in a locked position distally aboutthe lesion for guiding a surgeon down the wire to the lesion site duringsubsequent surgery. While such a location system is effective, it isobviously intended and designed to be only temporary, and is removedonce the surgery or other procedure has been completed.

Other devices are known for marking external regions of a patient'sskin. For example, U.S. Pat. No. 5,192,270 to Carswell, Jr. discloses asyringe which dispenses a colorant to give a visual indication on thesurface of the skin of the point at which an injection has or will begiven. Similarly, U.S. Pat. No. 5,147,307 to Gluck discloses a devicewhich has patterning elements for impressing a temporary mark in apatient's skin, for guiding the location of an injection or the like. Itis also known to tape or otherwise adhere a small metallic marker, e.g.a 3 millimeter diameter lead sphere, on the skin of a human breast inorder to delineate the location of skin calcifications (see Homer etal., The Geographic Cluster of Microcalcifications of the Breast,Surgery, Gynecology, & Obstetrics, Dec. 1985). Obviously, however, noneof these approaches are useful for marking and delineating internaltissue abnormalities, such as lesions or tumors.

Still another approach for marking potential lesions and tumors of thebreast is described in U.S. Pat. No. 4,080,959. In the describedprocedure, the skin of the portion of the body to be evaluated, such asthe breasts, is coated with a heat sensitive color-responsive chemical,after which that portion of the body is heated with penetratingradiation such as diathermy. Then, the coated body portion is scannedfor color changes which would indicate hot spots beneath the skinsurface. These so-called hot spots may represent a tumor or lesion,which does not dissipate heat as rapidly because of its relatively poorblood circulation (about 1/20 of the blood flow through normal bodytissue). This method, of course, functions as a temporary diagnostictool, rather than a permanent means for delineating the location of atumor or lesion.

A method of identifying and treating abnormal neoplastic tissue orpathogens within the body is described in U.S. Pat. No. 4,649,151 toDougherty et al. In this method, a tumor-selective photosensitizing drugis introduced into a patient's body, where it is cleared from normaltissue faster than it is cleared from abnormal tissue. After the drughas cleared normal tissue but before it has cleared abnormal neoplastictissue, the abnormal neoplastic tissue may be located by theluminescence of the drug within the abnormal tissue. The fluorescencemay be observed with low intensity light, some of which is within thedrugs absorbance spectrum, or higher intensity light, a portion of whichis not in the drugs absorbance spectrum. Once detected, the tissue maybe destroyed by further application of higher intensity light having afrequency within the absorbance spectrum of the drug. Of course, thismethod also is only a temporary means for marking the abnormal tissue,since eventually the drug will clear from even the abnormal tissue.Additionally, once the abnormal tissue has been destroyed duringtreatment, the marker is destroyed as well.

It is also known to employ biocompatible dyes or stains to mark breastlesions. First, a syringe containing the colorant is guided to adetected lesion, using an imaging system. Later, during the extractionprocedure, the surgeon harvests a tissue sample from the stained tissue.However, while such staining techniques can be effective, it isdifficult to precisely localize the stain. Also, the stains aredifficult to detect fluoroscopically and may not always be permanent.

Additionally, it is known to implant markers directly into a patient'sbody using invasive surgical techniques. For example, during a coronaryartery bypass graft (CABG), which of course constitutes open heartsurgery, it is common practice to surgically apply one or more metallicrings to the aorta at the site of the graft. This enables a practitionerto later return to the site of the graft by identifying the rings, forevaluative purposes. It is also common practice to mark a surgical sitewith staples, vascular clips, and the like, for the purpose of futureevaluation of the site.

A technique has been described for the study of pharyngeal swallowing indogs, which involves permanently implanting steel marker beads in thesubmucosa of the pharynx (S. S. Kramer et al., A Permanent RadiopaqueMarker Technique for the Study of Pharyngeal Swallowing in Dogs,Dysphagia, Vol. 1, pp. 163-167, 1987). The article posits that theradiographic study of these marker beads during swallowing, on manyoccasions over a substantial period of time, provides a betterunderstanding of the pharyngeal phase of degluitition in humans. In thedescribed technique, the beads were deposited using a metal needlecannula having an internal diameter slightly smaller than the beads tobe implanted. When suction was applied to the cannula, the bead satfirmly on the tip. Once the ball-tipped cannula was inserted throughtissue, the suction was broken, thereby releasing the bead, and thecannula withdrawn.

Of course, this technique was not adapted or intended to mark specifictissue sites, but rather to mark an entire region or structure of thebody in order to evaluate anatomical movements (i.e., swallowingmotions). It also was not intended for use in humans.

Accordingly, what is needed is a method and device for non-surgicallyimplanting potentially permanent markers at the situs of a lesion orother abnormal tissue, for the purpose of defining the margins of alesion before it is removed and/or to establish its location after ithas been removed. The markers should be easy to deploy and easilydetected using state of the art imaging techniques.

SUMMARY OF THE INVENTION

This invention solves the problems noted above by providing animplantable device which is particularly adapted to mark the location ofa biopsy or surgery for the purpose of identification. The device isremotely delivered, preferably percutaneously. Visualization of themarker is readily accomplished using various state of the art imagingsystems. Using the invention, it is possible to permanently mark thelocation or margins of a lesion or other tissue site, prior to removingor sampling same. The markers function to provide evidence of thelocation of the lesion after the procedure is completed, for referenceduring future examinations or procedures.

More particularly, a device is provided for marking tissue within ahuman body to identify a selected location for a diagnostic ortherapeutic procedure. The device comprises a marker element and anapparatus for remotely delivering the marker element from outside thehuman body to the selected tissue location. Since, with remote delivery(e.g. percutaneously) direct visual access is not possible, an aidedvisualization device is used, such as an imaging system, an endoscope,or the like. Deployment of the marker element is such that it becomesimplanted in the tissue.

The delivery apparatus preferably includes a member, which may comprisea tube, such as a needle, cannula, or trocar, of any known type fordelivering medications, surgical equipment, or other items to theinterior of a patient's body. The member may also be the body of anoptical instrument such as an endoscope, laparoscope, or arthroscope. Inthe preferred embodiment, a biopsy needle or gun, such as is often usedto extract tissue for examination in a biopsy procedure, is used inconjunction with the marking device, comprising a portion of thedelivery apparatus, in order to provide a means for entering thepatient's body and positioning the marker element at the selected tissuelocation. However, in other embodiments, the marking device is selfcontained, having a means itself for obtaining entry to the body, andbeing guided by a commercially available guidance system, such as astereotactic guidance system.

The aforementioned member or tube, which typically comprises a cannulaor needle having a lumen, has a distal end portion or region and aproximal end portion or region, and is adapted to extend through thebody. The distal region is adapted to retain and deploy the markerelement and the proximal region is linked to the distal region, so thatpredetermined marker deployment functions may be communicated from theproximal region to the distal region. In some embodiments, thesedeployment functions are communicated by means of the marker elementsthemselves traveling through the lumen for deployment from the distalregion. In other embodiments, an actuator extends axially through thelumen to communicate deployment functions to the marker element held onor by the distal region. The apparatus is preferably guided to theselected tissue location, i.e., the site of the detected lesion or otherabnormality, using a stereotactic guidance system or similar imagingsystem.

Several alternative embodiments of the marking device are disclosed. Inone embodiment, the distal region of the tube includes a forming die,which is adapted to form each marker element into a predetermined shape,preferably a helix, as the marker element is deployed from the lumen. Ina number of alternative embodiments, a mechanism, such as a mandrel, isused to push the marker elements through the tube. The marker elementsmay comprise a pre-formed spring having a predetermined shape, which iscompressed into a linear position within the tube lumen. Upon deploymentfrom the lumen, the spring is adapted to expand and assume itspredetermined shape to such an extent that the energy of its expansionis sufficient to implant the marker element into the tissue at theselected tissue location. In some embodiments, implantation isaccomplished because the marker elements have a plurality of attachmentelements, each having a tip end (sometimes sharpened) which expandsoutwardly with sufficient energy to embed and anchor itself into thetissue at the selected tissue location. In other embodiments, the markerelement has blunt, rather than sharpened edges, but is adapted to expandsufficiently upon exiting from the tube that its edges press radiallyagainst the selected tissue, thereby wedging and implanting the markerelement.

In yet another embodiment of the invention, the tube lumen is adapted toreceive a deployment actuator connector, or center wire, which extendsaxially through the lumen. The connector includes a distal portion whichextends distally of the tube and a proximal portion which extendsproximally of the tube. The proximal portion is attached to a deploymentactuator, such as a pull ring, while the distal portion is attached tothe marker element. On the connector, proximal to the distal portion, isa predetermined failure point which is adapted to be the weak point onthe connector by failing first under tension. In operation, once thetube distal region has been positioned at the selected tissue location,the deployment actuator is actuated in a proximal direction to pull themarker element against the distal region of the tube. The tube distalregion thus functions as a forming die to cause the marker element tobend until it abuts the tube distal region at its junction with thedistal portion of the connector, such that the marker element isreconfigured to a desired shape. The proximal portion of the connectoris adapted to be severed from the distal portion at the predeterminedfailure point upon the application of continued tension on thedeployment actuator after abutment of the marker element against thetube distal region, thereby releasing and implanting the marker element.

Another important feature of the invention is the ability to utilizemarker elements having a plurality of shapes. In some embodiments, theseshapes may be created merely by utilizing different sized material stockor different cross sections. This shape diversity permits the adoptionof a system wherein each shape denotes a different selected tissuelocation or event.

In a preferred embodiment of the invention, the device is adapted to beemployed in combination with a medical instrument which transports thedevice to the selected tissue location responsive to positional controlby a guidance system. The medical instrument preferably draws a vacuumto isolate and retain tissue at the selected location in a tissuereceiving port. The marking device is adapted to deploy the markerelement into the retained tissue.

In another aspect of the invention, a marker element is provided formarking tissue within a human body to identify a selected location for adiagnostic or therapeutic procedure. The marker element, which ispreferably comprised of a biocompatible, implantable, and substantiallyradiopaque material, is adapted to be deployed to the selected tissuelocation percutaneously by a delivery instrument, so as to becomeimplanted in the tissue.

A number of different marker element configurations and materials may beemployed. Materials may include stainless steel, titanium, and the like,as well as non-metallic materials, such as polymers, salts, andceramics, for example. In some embodiments, the marker element mayactually be formed into a desired shape by a forming die in the deliveryinstrument, while in other embodiments, it may comprise a spring whichradially expands upon exit from the delivery instrument to embed itselfin the tissue.

In yet another aspect of the invention, a method for permanently markingtissue in a human body to identify a selected location for a diagnosticor therapeutic procedure is disclosed, which comprises actuating adelivery instrument, having a tube with a distal region, to a positionwherein the tube extends through the human body and the distal region isat the selected location. A marker element is then deployed from thetube distal region to the selected tissue location so that it becomesanchored in the tissue.

These and other aspects and advantages of the present invention are setforth in the following detailed description and claims, particularlywhen considered in conjunction with the accompanying drawings in whichlike parts bear like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a biopsy instrument embodiment asdescribed in co-pending patent application Ser. No. 08/217,246,configured to be utilized as a preferred instrument for use inconjunction with the inventive tissue marking device;

FIGS. 2 and 3 are cross-sectional views illustrating the sequentialsteps in the operation of the biopsy instrument embodiment needed tocapture tissue targeted for marking;

FIG. 4 is a cross-sectional view of one embodiment of a tissue markingdevice constructed in accordance with the principles of the invention,illustrating the device in a first position in preparation fordelivering a marker to tissue targeted for marking;

FIGS. 5, 6, 7, and 8 are cross-sectional views similar to FIG. 4,illustrating sequentially the delivery of a marker to the targetedtissue;

FIGS. 9, 10, and 11 are schematic cross-sectional views of analternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention, illustratingsequentially the delivery of a marker to the targeted tissue;

FIG. 12 is a schematic cross-sectional view illustrating a thirdalternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention;

FIG. 13 is a schematic cross-sectional view illustrating a fourthalternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention;

FIG. 14 is a schematic cross-sectional view illustrating a fifthalternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention;

FIG. 15 is a schematic cross-sectional view illustrating a sixthalternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention;

FIG. 16 is a schematic cross-sectional view illustrating a seventhalternative embodiment of a tissue marking device constructed inaccordance with the principles of the invention;

FIG. 17 is a front elevation view of an alternative marker elementembodiment;

FIG. 18 is a perspective view of another alternative marker elementembodiment;

FIG. 19 is a front elevation view of yet another alternative markerelement embodiment; and

FIG. 20 is a front elevation view of still another alternative markerelement embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Now with more particular reference to the drawings, FIGS. 4-8 illustratesequentially the deposit of a marker into a desired tissue location,utilizing a preferred embodiment of the invention. Specifically, themarking instrument 10 comprises a marker element 12 which includes anumbrella end comprising a pair of attachment members or wings 14 and 16,and a center wire 18. All three wires 14, 16 and 18 are joined at thedistal end 20 of the center wire 18, preferably by welding. At theproximal end 22 of the center wire is a deployment actuator or pull ring24, which is preferably attached by welding or brazing.

To place the marker element 12 at a desired location, a biopsy needle orgun is preferably used, though other known delivery means could be usedas well. For example, the stand-mounted biopsy instrument described inU.S. patent application Ser. No. 08/217,246, previously incorporated byreference into this application, is a preferred instrument forintroducing the marker element into the body of a patient. Oneembodiment of such an instrument 26 is partially illustrated in FIGS.1-3. The biopsy instrument 26 includes a housing 28. A hollow outerpiercing needle 38 is attached to the housing 28 at location 34. Adistal end of the hollow outer piercing needle 38 includes a point 40.Hollow outer piercing needle 38 also includes a tissue receiving port orbowl 42 (FIGS. 2 and 3). A cannular inner cutter 44 is movablypositioned coaxially within the hollow outer piercing needle 38 andhousing 28. A vacuum line 46 supplies vacuum to ports 50 in the bottomof the receiving bowl 42.

Operation of the biopsy instrument to facilitate the placement of atissue marker is illustrated sequentially in FIGS. 1-3. FIG. 1illustrates the distal end point 40 of the hollow outer piercing needle38 in position to pierce a target tissue 51. The initial position of thepoint 40 with respect to the tissue area being marked is determined bythe overall position of the biopsy instrument with respect to thepatient. For example, the entire biopsy instrument may be mounted on acommercially available stereotactic guidance system (not shown) commonlyused in the medical field for accurate positioning of a variety ofmedical devices with respect to a patient. A detailed description ofsuch a motorized biopsy needle positioner, i.e., stereotactic guidancesystem, is given in U.S. Pat. No. 5,240,011, issued on Aug. 31, 1993 toMichael Assa, which is hereby incorporated herein by reference. Thesuspect lesion within tissue 51 is to be targeted and marked accordingto the instructions provided with the stereotactic guidance system. Asshown in FIG. 1, the stereotactic guidance system has positioned thebiopsy instrument 26 such that the distal end point 40 is immediatelyadjacent to the surface of the tissue 51. Once the point 40 is adjacentthe specific lesion to be marked, the needle 38 is fired into the lesionsuch that the point 40 traverses through the lesion, thereby placing thetissue receiving bowl 42 in the center of the lesion.

As shown in FIG. 2, after the hollow outer piercing needle 38 has beenpositioned at the precise location within the tissue 51 at which it isdesired to mark tissue, the cutter 44 is moved proximally of the housing28 to provide an entry access for the tissue marker delivery system.

As shown in FIG. 3, a vacuum source attached to vacuum line 46 isactuated, thereby generating a region of low pressure at the vacuumports 50 to facilitate the prolapse of tissue 51 a immediately adjacentto the tissue receiving port 42 into the hollow interior of hollow outerpiercing needle 38.

Now again referring to FIGS. 4-8, the marking instrument 10 includes atube 54. The center wire 18 runs axially through a lumen 56 of the tube54, with the pull ring 24 being attached to the proximal end of thecenter wire 18, proximally of the tube 54. The distal end 20 of thecenter wire extends distally of the tube 54 and is joined to attachmentmembers 14 and 16, as described above.

In operation, the tube 54 of the marking instrument is inserted into thepatient's body in the direction of the arrow 58, as shown in FIG. 4,until the distal end 20 of the center wire 18 approaches the desiredlocation, adjacent to or in the abnormal tissue or lesion. Becausedirect visual access to the targeted tissue is impossible, an aidedvisualization device, such as the stereotactic guidance system describedabove, is used to guide the distal portion of the marking instrument tothe targeted tissue. Then, if the biopsy instrument shown in FIGS. 1-3is utilized to deploy the markers, the targeted tissue 51 a (FIG. 5) isvacuumed into the tissue receiving port 42. Referring particularly toFIG. 5, once the distal end 20 of the center wire reaches the targeted,vacuumed tissue, the ring 24 is pulled away from the tissue in thedirection of the arrow 60. This action deploys the marker attachmentmembers 14 and 16 as they are forced into a die formed in the tip 62 ofthe tube. This die may take any desired form, depending upon the desireddeployed configuration of the attachment members 14, 16.

With reference to FIG. 6, tension continues to be applied to the ring24, in the direction shown by the arrow 64, until the distal end of themarker is fully deployed. Forcing the attachment members into the die 62causes them to extend outwardly, as illustrated, into the tissue. Theiroutward energy anchors the marker element 12 in the tissue for permanentimplantation. The tips 66 and 68 of the attachment members may beconfigured to be less traumatic as an implant, or may alternatively besharpened to provide a more secure grip. At full deployment, the widthof the umbrella end of the marker element is preferably about 0.035 to0.045 inches, though other sizes may be utilized within the scope of theinvention.

Now referring to FIG. 7, even after the attachment members 14 and 16have been fully deployed, the pull ring 24 is pulled to further increasetension in the direction of the arrow 70, until the center wire 18 issheared at a point of weakness or detent 72 (see FIGS. 4-6) which isestablished in the center wire 18 proximally of the tip 20. Once failurehas occurred, the pull ring 24 and the proximal portion 18′ of thecenter wire may be discarded as they are severed from the marker element12 and remaining distal portion 18″ of the center wire.

Finally, with reference to FIG. 8, to finish placing the marker element12, the tube 54 is withdrawn in the direction of the arrow 74, asillustrated. The marker element is thereby permanently secured to locatethe lesion site for future examination by known imaging methods.

In the preferred embodiment, the marker element 12 is fabricated ofstainless steel. However, many other biocompatible, radiopaque,implantable materials may be used for the marker element 12 as well,including, for example, titanium, tantalum, or nickel-titanium alloys.Additionally, while a 3-pronged umbrella end is shown and described, anynumber of prongs may be used, if desired.

While it is preferred that the marker element 12 be deployed using thebiopsy instrument described and shown in FIGS. 1-3, any instrumentcapable of delivering the element percutaneously may be utilized. Suchinstruments, for example, may include the hand-held biopsy gun describedin U.S. Pat. No. Re. 34,056, entitled “TISSUE SAMPLING DEVICE” andissued to Lindgren et al. All of these types of instruments include atube (typically a cannula or needle) which is adapted to enter the body,and would be capable of delivering the marker element. It is also withinthe scope of the invention to deliver the marker element through anytube which has access to the body or using optical medical instruments,such as endoscopes, arthroscopes, or laparoscopes, in which case themarker element is delivered to the desired tissue site from outside thebody of the patient, through the body of the instrument.

Now with reference to FIGS. 9-11, an alternative embodiment of a markinginstrument 10 a is shown, which is identical to the instrument 10 in allrespects not shown or described herein. Portions of the instrument 10 acorresponding to portions of the instrument 10 are designated bycorresponding reference numerals followed by the letter a.

The FIG. 9 embodiment is substantially similar to the FIG. 4 embodiment,in that the marking instrument includes a tube 54 a which has a lumen 56a, and may utilize a cannula, needle, or imaging instrument (i.e.,endoscope, laparoscope, or the like) for access to a delivery sitewithin the body and to aid in delivery. Again, as is the case for allsucceeding embodiments, it is preferred that the tube 54 a utilize thehollow outer piercing needle 38 of the biopsy instrument shown in FIGS.1-8, though any other instrument which is capable of delivering a markerpercutaneously or through a body orifice from a location outside thepatient's body may be utilized. A center wire 18 a runs longitudinallythrough the lumen 56 a. At the proximal end of the center wire 18 a is adeployment actuator or pull ring 24 a. At the distal end of the centerwire is the marker element 12 a.

A primary difference between the FIG. 4 and FIG. 9 embodiments is thatthe FIG. 9 marker element 12 a is preferably a generally “U” shapedelement resembling a surgical ligating clip, having tips 66 a and 68 a,which is captured by the distal looped end 20 a of the twisted centerwire. In operation, once the tips 66 a and 68 a of the marking element12 a reach the targeted tissue, the ring 24 a is pulled rightwardly inthe direction of the arrow 76 (FIG. 10). This action retracts the baseportion 78 of the marker element 12 a into a forming recess 80 (FIG. 9),wherein the recessed tube wall 82 forces prongs 86 and 88 together untiltips 66 a and 68 a of the prongs 86 and 88, respectively, contact ornearly contact one another (FIG. 10). At this point, increasing tensionapplied to the pull ring 24 a causes the wire 18 a to fail at a point ofweakness or detent (not shown) provided in the center wire at or nearits tip end 20 a, thereby releasing the marker into the target tissue,as illustrated in FIG. 11.

Referring now to FIG. 12, a second alternative embodiment of a markinginstrument 10 b is shown, which is identical to the instrument 10 in allrespects not shown or described herein. Portions of the instrument 10 bcorresponding to portions of the instrument 10 are designated bycorresponding reference numerals followed by the letter b.

The FIG. 12 embodiment is substantially similar to the FIG. 4embodiment, in that the marking instrument includes a tube 54 b whichhas a lumen 56 b, and may utilize a cannula, needle, or imaginginstrument (i.e., endoscope, laparoscope, or the like) for access todelivery site within the body and to aid in delivery.

There are two primary differences between the embodiments of FIGS. 4 & 9and that of FIG. 12. First, in the FIG. 12 embodiment, a plurality ofmarker elements 12 b (two are shown, though any number may be employed)may be preloaded into the tube 54 b, each comprising a pre-formed springwhich is deployed through the tube's distal region 90 in an axialdirection. Second, the nature of the deployment mechanism utilizes acompressive rather than tensile force. It may further be noted that,though end deployment of the marker elements in the FIG. 12 embodimentis illustrated, they may be similarly deployed radially through a sideport (not shown) in tube 54 b, or at any other angle, to accommodatedelivery through an existing instrument (i.e., cannula, needle,endoscope, laparoscope, or the like). In being deployed radially, thedistal region 90 is not used for passage of the marker element and couldbe utilized to house a piercing element (not shown) similar to thatshown in FIGS. 1-3. Armed with the piercing element, this markerdelivery system would not be dependent on a positioning system asdescribed in FIGS. 1-3 for placement at the tissue site and could beused alone in conjunction with a commercially available stereotactic orother guidance system. This concept may be applied to all subsequentembodiments except that illustrated in FIG. 16.

Still with reference to FIG. 12, each marker element or spring 12 bpreferably includes a center coil 92 from which a pair of attachmentmembers 94 and 96 extend, and is adapted to automatically attach itselfto the target tissue by utilizing its own stored energy. Thus, inoperation, each spring 12 b is held in a compressed position within thetube 54 b. When it is desired to deploy the marker, a mandrel 98 ispreferably utilized to push the spring 12 b through the center lumen 56b and out through the distal open end 90 of the tube. Once the springexits the tube, stored energy causes the attachment members 94 and 96 toexpand outwardly, as shown. As this expansion occurs, the tips 102 and104 of the attachment members 94 and 96, respectively, anchor themselvesinto the tissue to permanently secure the marker element in the desiredlocation. As with the FIG. 4 embodiment, the tips 102 and 104 may beblunt to be less traumatic as an implant, or may alternatively besharpened or barbed to provide a more secure grip. Once a spring hasbeen deployed, the instrument may be repositioned to the next desiredlocation for the immediate deployment of another marker until the supplyin the tube 54 b is exhausted, eliminating the need to remove andre-load the marking instrument 10 b between each deployment.

Again in this embodiment, the spring 12 b may be fabricated of any knownbiocompatible, implantable, radiopaque material, though stainless steelis preferred. Additionally, the forces required to deploy the attachmentmembers on the spring may be customize by varying the spring filar,dimensions, material, and/or the number of coils in the torsional partof the spring.

FIG. 13 illustrates another alternative embodiment of the markinginstrument 10, which is identical to the instrument 10 b of FIG. 12 inall respects not shown or described herein. Portions of the instrument10 c corresponding to portions of the instrument 10 b of FIG. 12 aredesignated by corresponding reference numerals followed by the letter c.

In actuality, the FIG. 13 embodiment is substantially identical to thatof FIG. 12, except for the shape of each spring 12 c, and is employed inprecisely the same manner. Thus, to deploy a marker element 12 c, themandrel 98 c is utilized to push the spring 12 c through the centerlumen 56 c and out through the distal open end 90 c of the tube. As inthe FIG. 12 embodiment, the marker element travels in the direction ofthe arrow 100 c, until the attachment members 94 c and 96 c extendoutwardly sufficiently to anchor themselves to the target tissue. Also,the FIG. 13 embodiment is similar to the FIG. 12 embodiment in that theinstrument may be re-positioned to immediately deploy another markerelement without re-loading, and marker elements may be deployed radiallythrough a side port in tube 54 c (not shown), or any other angle, toaccommodate delivery through an existing instrument (i.e., cannula,needle, endoscope, laparoscope, or the like).

FIG. 14 shows still another alternative embodiment of the markinginstrument 10, which is also substantially identical to the instrument10 b of FIG. 12 in all respects not shown or described herein. Portionsof the instrument 10 d corresponding to portions of the instrument 10 bof FIG. 12 are designated by corresponding reference numerals followedby the letter d.

Again, the FIG. 14 embodiment is substantially identical to those ofFIGS. 12 and 13, except for the shape of the marker element or spring 12d. A marker element 12 d is deployed preferably using a mandrel 98 d orthe like to push the spring 12 d through the center lumen 56 d until itexits through the open end 90 d of the tube. As in the FIGS. 12 and 13embodiments, the marker element travels in the direction of the arrow100 d, until the tips 102 d and 104 d extend outwardly sufficiently toanchor themselves to the target tissue.

In practice, a radiologist or other operator of the equipment can use amarker shaped like marker 12 b, as shown in FIG. 12, during one biopsy,then use a differently shaped marker, such as the marker 12 c in theFIG. 13 embodiment, or the marker 12 d in the FIG. 14 embodiment, duringa subsequent biopsy procedure. The differently shaped markers permit thedistinction between different biopsy procedures during future imagingprocedures, as well as between biopsy sites which may be close inproximity, thereby improving the information available to theradiologist and thus the ability to monitor or diagnose the patient'sfuture condition more precisely.

FIG. 15 illustrates yet another alternative embodiment of the markinginstrument 10, which is also substantially identical to the instrument10 b of FIG. 12 in all respects not shown or described herein. Portionsof the instrument 10 e corresponding to portions of the instrument 10 bof FIG. 12 are designated by corresponding reference numerals followedby the letter e.

In this embodiment, each marker element 12 e is deployed distallythrough the open distal region 90 e of the tube 54 e by a mandrel 98 e,much as in the previous embodiments shown in FIGS. 12, 13, and 14. Theprimary difference, however, between this embodiment and the previousembodiments is that, while the marker elements in the previousembodiments rely largely on the barbed nature of the spring to securethemselves in the tissue, in this embodiment, the springs are securedsimply because of their significant expansion upon exit from the tube.This embodiment particularly lends itself to marking the boundaries of abiopsy or other desired site by defining the perimeter of the site. Theexpansion of the spring 12 e causes the blunt edges 102 e and 104 e topress outwardly against the selected tissue, thereby wedging the springsecurely into position.

An advantage of this embodiment is that, because of the tightcompression of the springs 12 e within the tube 54 e, a larger number ofmarkers can be inserted therein simultaneously, thereby permitting thedeployment of more markers without having to pause and disengage toreload.

Another advantage the FIG. 15 embodiment provides is the ability todeploy springs adapted to expand to a number of different sizes all fromthe same lumen. Larger sized springs would require more coils within agiven lumen than smaller sized springs (not shown).

It should be noted that the springs need not be limited to theconfiguration illustrated, but could include any spring of anyconfiguration which expands to secure its position. While stainlesssteel is presently preferred, any other biocompatible, implantable, andradiopaque material could be used alternatively. Also as in the previousembodiments, marker elements may be similarly deployed radially througha side port in tube 54 e (not shown), or any other angle, to accommodatedelivery through an existing instrument (i.e., cannula, needle,endoscope, laparoscope, or the like).

Still another alternative embodiment of the marking instrument 10 isshown in FIG. 16. In this embodiment, the marking instrument 10 fcomprises a tube 54 f. Wire segments 106 of any desired length arepreloaded into the lumen 56 f, which runs along substantially the entirelength of the tube 54 f. Once the needle is properly positioned, themarker elements 12 f are deployed by pushing them out of the tip of theneedle, through the side exit port 108. A curved portion 110 of thelumen 56 f comprises a die portion, and is adapted to form the wiresegments 106 into helical marker elements 12 f as they passtherethrough, pushed by a mandrel (not shown) or other known means fromthe tip of the needle through the exit port 108. The nature of the curveor curves in the die portion 110 and preformed curves imparted into thewire segments determine the final shape (which resembles a partial orwhole helix) and dimensions of the marker element.

This embodiment is versatile in that it is capable of continuouslydeploying any number of marker elements without the necessity ofre-loading, since all that is required is a continuous feed of wiresegments into the proximal region of the tube 54 f. Furthermore,differently sized and shaped helixes may be delivered in the sameprocedure by utilizing marker wires of different diameters and/orpreformed curves, which approximate different helical shapes as theypass through the die portion. Thus, loading a plurality of differentsized wires into the needle yields a plurality of different shapedmarkers.

Of course, as with the previous embodiments, although stainless steel ispresently preferred, many different types of biocompatible, implantable,and radiopaque materials could be utilized within the scope of theinvention. Also as in the previous embodiments, marker elements may besimilarly deployed at different angles to accommodate delivery throughan existing instrument (i.e., cannula, needle, endoscope, laparoscope,or the like).

Unlike previous embodiments, FIG. 16 preferably incorporates a piercingelement 112 enabling this marker to be delivered without the aid of thepositioning system described in FIGS. 1-3 for placement at the tissuesite. This embodiment could be used alone in conjunction with acommercially available stereotactic or other (i.e., ultrasonic) guidancesystem.

Though a number of different embodiments of the conceptual inventionhave been described and shown, it is considered to be within the scopeof the invention for the marking elements and delivery instruments totake on many other forms. For example, embolization coils like thatillustrated in FIG. 17 and designated with reference numeral 12 g arewell known in the medical field for placement into vessels such as veinsand arteries in order to block off fluid flow abnormalities (such asfistulas and arteriovenous malformations). These coils have been made ofvarious materials, including stainless steel, platinum, and gold, andare wound into configuration similar to that of a light bulb filament.They are generally placed into the body using a catheter or trocarsystem. The inventors in the present application have discovered thatsuch coils may indeed also be used as marker elements, for permanentimplantation in target tissue, in a manner similar to that describedpreviously with respect to FIGS. 1-16.

Marker elements of many other materials and configurations may be usedas well. For example, one such multi-appendaged jack-shaped marker 12 his illustrated in FIG. 18. Additionally, small beads 12 i (FIG. 19) ofcalcium carbonate or other radiodense materials, which are highlyvisible by mammographic imaging, could be deployed as marker elements.One such application would be to place a plurality of such beads orpellets (each having a diameter of about 500 .mu.) around the entiretyof a breast lesion prior to the extraction procedure, which would thenserve as guides to ensure that all of the margins had been removed.During subsequent imaging procedures, they would function to denote thelocation of the previous biopsy for reference purposes.

Referring now to FIG. 20, yet another alternative marker element 12 j,which is of a woven construction, is illustrated. Other such markermaterials may include adhesives and epoxies which would be injected atthe biopsy site. Biodegradable polymers and other plastics could also beused, as long as they are biocompatible, implantable, and visible usingan imaging system.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

1. A method for breast biopsy, comprising the steps of: providing abiodegradable radiodense implant; taking a tissue sample from a breastof a patient to create a biopsy site; positioning the biodegradableradiodense implant within the biopsy site; testing the tissue sample;and relocating the biopsy site by detecting the biodegradable radiodenseimplant.
 2. The method of claim 1, wherein the entire implant isradiodense.
 3. The method of claim 1, wherein the entire implant isbiodegradable.
 4. The method of claim 1, further comprising an adhesive.5. The method of claim 1, wherein the implant is a plastic.
 6. Themethod of claim 1, wherein the implant comprises a plurality of beads orpellets.
 7. The method of claim 6, wherein a diameter of a bead orpellet is about 500 μm.
 8. A method for breast biopsy, comprising thesteps of: providing a biodegradable implant having a radiodensematerial; taking a tissue sample from a breast of a patient to create abiopsy site; positioning the biodegradable implant having a radiodensematerial within the biopsy site; testing the tissue sample; andrelocating the biopsy site by detecting the biodegradable implant havinga radiodense material.
 9. The method of claim 8, wherein the entireimplant is radiodense.
 10. The method of claim 8, wherein the entireimplant is biodegradable.
 11. The method of claim 8, further comprisingan adhesive.
 12. The method of claim 8, wherein the implant is aplastic.
 13. The method of claim 8, wherein the implant comprises aplurality of beads or pellets.
 14. The method of claim 13, wherein adiameter of a bead or pellet is about 500 μm.
 15. A method for breastbiopsy, comprising the steps of: providing a biodegradable implant thatis visible using an imaging system; taking a tissue sample from a breastof a patient to create a biopsy site; positioning the biodegradableimplant that is visible using an imaging system within the biopsy site;testing the tissue sample; and relocating the biopsy site using theimaging system by detecting the biodegradable implant.
 16. The method ofclaim 15, wherein the implant is radiodense.
 17. The method of claim 15,wherein the entire implant is radiodense.
 18. The method of claim 15,wherein the entire implant is biodegradable.
 19. The method of claim 18,wherein the imaging system is a mammographic imaging system.
 20. Themethod of claim 15, wherein the implant is a plastic.